<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>3_回调ref中回调执行次数的问题</title>
    </head>
    <body>
        <!-- 准备好一个“容器” -->
        <div id="test"></div>

        <!-- 引入react核心库 -->
        <script type="text/javascript" src="../js/react.development.js"></script>
        <!-- 引入react-dom，用于支持react操作DOM -->
        <script type="text/javascript" src="../js/react-dom.development.js"></script>
        <!-- 引入babel，用于将jsx转为js -->
        <script type="text/javascript" src="../js/babel.min.js"></script>


        <script type="text/babel">
            //创建组件
            class Demo extends React.Component {

                state = {isHot: false}

                showInfo = () => {
                    const {input1} = this
                    alert(input1.value)
                }

                changeWeather = () => {
                    //获取原来的状态
                    const {isHot} = this.state
                    //更新状态
                    this.setState({isHot: !isHot})
                }

                saveInput = (c) => {
                    this.input1 = c;
                    console.log('@外面', c);
                }

                render() {
                    const {isHot} = this.state
                    return (
                        <div>
                            <h2>今天天气很{isHot ? '炎热' : '凉爽'}</h2>
                            {/* 注意注释写法 这种写法会多次执行 并且参数值为null 影响不大  解决办法写到外面
                            <input ref={(c)=>{this.input1 = c;console.log('@',c);}} type="text"/><br/><br/>*/}
                            <label>
                                <input ref={(c) => {
                                    this.input1 = c;
                                    console.log('@里面', c);
                                }} type="text"/>
                            </label>
                            <br/><br/>

                            {/*-- 解决办法写到外面*/}
                            <label>
                                <input ref={this.saveInput} type="text"/>
                            </label>
                            <br/><br/>
                            <button onClick={this.showInfo}>点我提示输入的数据</button>
                            <button onClick={this.changeWeather}>点我切换天气</button>
                        </div>
                    )
                }
            }

            //渲染组件到页面
            ReactDOM.render(<Demo/>, document.getElementById('test'))
        </script>
    </body>
</html>